In conventional backlight modules of liquid crystal display (LCD) devices, printed circuit boards (PCBs) are fixed by screws, and supporting posts are used to abut against reflective sheets and support diffuser plates. However, assembling a backlight module in this way requires a large number of screws and consumes much labor and metal materials; furthermore, because of the small areas of the screws and the supporting posts, the stressed surface areas are also small, which tends to cause protruding or warping of the PCB.
In backlight modules of prior art, the screws and the supporting posts may cause protruding or warping of the reflective sheet and the PCB, which tends to cause deformation of the backplate of the backlight module due to a non-uniform force distribution. Moreover, in the conventional backlight modules, an end of each supporting post protrudes out of the backplate, which is unfavorable for achieving an aesthetic appearance.